YOU SAID:
You be the prince and I'll be the princess
INTO JAPANESE
あなたは王子様、私はお姫様になります
BACK INTO ENGLISH
you'll be a prince, i'll be a princess
INTO JAPANESE
あなたは王子様になる、私はお姫様になる
BACK INTO ENGLISH
you'll be a prince, i'll be a princess
That didn't even make that much sense in English.